private void BuildParameters(CommandAttribute attribute, ParameterInfo[] parameterInfo)
{
if (parameterInfo.Length == 0)
{
throw new CommandException($"No parameters for CommandHandler {string.Join(',', attribute.Commands)}, ICommandContext must at least be supplied!");
}
// first parameter must be the context
if (!typeof(ICommandContext).IsAssignableFrom(parameterInfo[0].ParameterType))
{
throw new CommandException($"First parameter for CommandHandler {string.Join(',', attribute.Commands)} must be ICommandContext!");
}
var builder = ImmutableList.CreateBuilder <CommandParameter>();
foreach (ParameterInfo parameter in parameterInfo.Skip(1))
{
Type underlyingType = Nullable.GetUnderlyingType(parameter.ParameterType);
// if parameter has the ParameterAttribute attribute the converter overload will be used from here
// otherwise it will come from the default for the parameter type
ParameterAttribute parameterAttribute = parameter.GetCustomAttribute <ParameterAttribute>();
IParameterConvert converter = parameterAttribute?.Converter != null
? CommandManager.Instance.GetParameterConverter(parameterAttribute.Converter)
: CommandManager.Instance.GetParameterConverterDefault(underlyingType ?? parameter.ParameterType);
if (converter == null)
{
throw new ArgumentException($"No parameter converter found for parameter {parameter.Name} in CommandHandler {string.Join(',', attribute.Commands)}!");
}
// parameter is considered optional if specified explicitly or if is a nullable type
builder.Add(new CommandParameter(parameter.ParameterType, converter, underlyingType != null || (parameterAttribute?.IsOptional ?? false)));
}
parameters = builder.ToImmutable();
// check that optional parameters are last
int index = parameters.FindIndex(p => p.IsOptional);
if (index == -1)
{
return;
}
for (int i = index; i < parameters.Count; i++)
{
if (!parameters[i].IsOptional)
{
throw new CommandException($"Optional parameters must come after mandatory parameters in CommandHandler {string.Join(',', attribute.Commands)}!");
}
}
}
/// <summary>
/// Create a new <see cref="CommandParameter"/> of the supplied <see cref="System.Type"/> with optional <see cref="IParameterConvert"/> overload and optional flag.
/// </summary>
public CommandParameter(Type type, IParameterConvert converter, bool isOptional)
{
Type = type;
Converter = converter;
IsOptional = isOptional;
}